There are a lot of reasons you could be feeling more pain these days – from disease activity to stress to simply “overdoing it.” But excess pounds, independent of these other factors, may also be a cause – and research in the journal Obesity adds to the growing body of evidence.

In fact, the more extra weight you’re carrying, the worse your pain may be. The recent study found that people in the most obese group were more than 2.5 times as likely to report pain than those with a normal body mass index, or BMI.

What’s more, “the BMI-pain association was steeper for females than males, and steeper for those older than 40 compared with younger people,” write lead authors Arthur A. Stone, PhD, and Joan E. Broderick, PhD, both professors in Stony Brook’s department of psychiatry and behavioral science.

The researchers analyzed data from telephone interviews of more than one million people, conducted by the Gallup Organization between 2008 and 2010, to compile their report.

Among the questions: “Did you experience physical pain a lot of the day yesterday?” The reason for that wording is because studies show the most valid and reliable self-reported data is gathered when people are asked to recall recent information. Broderick says it avoids “recall biases.”

“It’s a pretty fair representation of what the individual is experiencing,” Broderick says.

The study results show 36.8 percent of those surveyed had a low or normal BMI, 38.3 percent were considered overweight and 24.9 percent – one in four – were classified as obese.

Compared with people who have a BMI of 25 or less, overweight individuals (with a BMI between 25 to 30) reported 20 percent higher rates of pain. Among obese people, those with a BMI between 30 and 35 reported 68 percent higher rates of pain; those with a BMI between 35 and 40 had 136 percent higher rates of pain; and those with a BMI greater than 40 experienced 254 percent higher rates of pain.

Stone and Broderick found that an overweight person doesn’t need a chronic condition, like arthritis, to be in pain: Weight alone can be the cause.

“This relationship between being overweight and experiencing pain does not seem to be coming simply from musculoskeletal conditions where weight has an effect on joints and causes pain,” explains Broderick. “But our data suggests ... it goes in the other direction, so excess weight leads to pain.”
 

The study, which confirmed the results of other, smaller studies, addressed pain in general, but the researchers also discussed the pain associated with chronic pain conditions, like arthritis and other rheumatic diseases.

In addressing arthritis, the researchers acknowledged the chicken-or-egg conundrum. Stone and Broderick say that such debilitating diseases could keep patients from participating in physical activity, which makes them prone to weight gain.

But even when they controlled for the presence of a chronic condition, like arthritis, the association still remained, although it was “substantially reduced.”

Also noteworthy is that the effect of weight on pain intensified as the age group of the respondents increased.

“This [pain intensification] could suggest a developmental process,” Broderick says. “If you just think about it in terms of inflammation, if people are carrying excess weight and that is triggering an inflammation process – that could explain why the longer people are walking around with excess weight the more the inflammatory process is causing damage.”

That inflammatory process could be the handiwork of hormones – in particular, one called leptin. It’s best known as a hunger-regulating hormone released by fat tissue, but recent studies have linked increased leptin levels with inflammation and pain in people with arthritis. Stone and Broderick acknowledged leptin as a possible reason for the link between weight and pain in their study.

“There is emerging research that suggests that having more fat cells and fat tissue in the body triggers an inflammatory response and inflammation [which] could then contribute to pain for one reason or another,” Broderick explains.

Lawrence J. Cheskin, MD, director of the Johns Hopkins Weight Management Center in Baltimore, applauds the researchers for working to understand what is driving pain in people who are overweight and obese, but he says the bottom line remains the same for patients.

“The fact is – if you are obese for whatever set of reasons – you are more likely to have daily pain,” he says.

While he knows it can be daunting, he says losing weight is critical. “In addition to everything else we already know – [losing weight] has a good chance to make it less likely for you to have daily pain,” Dr. Cheskin says. “Someone with early arthritis – who is starting to get discomfort and [have limited movement] – if they lose weight they can do more because they weigh less and their arthritis may not progress to such disabling levels.”